Nippon Shokubai Co., Ltd.

Kazuhiko Sakamoto

Takeshi Nishimura

Sei Nakahara

Masatoshi Ueoka

Yukihiro Matsumoto

Osamu Dodo

Yoshitake Ishii

Kenji Sanada

Koji Ueno

Masao Baba

Naoki Serata

Tetsuji Mitsumoto

Takahiro Takeda

Hiroo Iwato

Kazuto Okazaki

Satoshi Nakagawa

Kouji Ueno

Hidefumi Haramaki

Masatsugu Kitaura

Fumio Shibusawa

Yoji Akazawa

Kazuo Ohkouchi

Tomohiro Nakae

Kunihiko Ishizaki

Kazushi Torii

Hirotama Fujimaru

Harunori Hirao

Masahiro Uemura

Masakatsu Mori

Kei Hamamoto

Hideki Sogabe

Kunihiko Suzuki

Yuichi Ijiri

Yohji Akazawa

Shigeru Sakamoto

Hiroyuki Ikeuchi

Satoshi Matsumoto

Yasuhisa Nakashima

Shin-Ichi Fujino

Makoto Nagasawa

Toyofumi Sakai

Mamoru Takamura

Misao Inada

Kenji Nakahara

Noriaki Mizutani

Takashi Sugimoto

Masaru Ishikawa

Naoto Kasaya

Ryoko Tahara

Shin-ichi Fujino

Hisao Nakama

Yuji Miyahara

Kazuo Okochi

Takashi Sera

Hiroaki Tanaka

A method for producing a polyacrylic acid (salt)-based water absorbent resin, sequentially including the steps of: storing or producing acrylic acid; mixing acrylic acid containing a polymerization inhibitor with water, a crosslinking agent, and optionally, a basic composition, and/or neutralizing them, to prepare an aqueous monomer solution; polymerizing the aqueous monomer solution; drying an obtained water-containing gel-like crosslinked polymer; and optionally carrying out surface crosslinking, wherein the acrylic acid containing the polymerization inhibitor has a water content of not higher than 1,000 ppm (by mass; the same applies hereinafter), and/or the aqueous monomer solution has a formic acid content of 1 to 700 ppm, relative to the monomer.

Polyacrylic acid (salt)-based water absorbent resin and method for producing same

An object of the present invention is to provide a particle-shaped water absorbing agent having a remarkably improved surface color and excellent water-absorbing properties (better water absorption capacity, and lower water soluble content and residual monomer content) at the same time. In order to attain the object, a particle-shaped water absorbing agent according to the present invention is a particle-shaped water absorbing agent whose main component is a polyacrylic acid and/or a salt thereof, the particle-shaped water absorbing agent having a surface color of Hunter b value in a range of &#x2212;5 to 10, and having a cross-linking absorption property index (CPI) in a range of 1 to 100, the CPI defined by the following two equations:=(+17)/Ln (water soluble content);&#x2003;&#x2003;Equation 1:=(/residual monomer content)&#xd7;100&#x2003;&#x2003;Equation 3:

Particle-shaped water absorbing agent and method for producing the same

A crystallization device and a crystallization process are provided for obtaining (meth)acrylic acid with higher purity without causing leakage of a crude solution by preventing complete clogging in a crystallization tube from occurring. The device for crystallizing (meth)acrylic acid includes a crude (meth)acrylic acid solution supply part, a crystallization tube, a heat medium supply tube, a heat medium discharge tube, a storage part of a crude (meth)acrylic acid solution passed through the crystallization tube, a tube for circulating and supplying the crude (meth)acrylic acid solution to the supply part from the storage part, and a pump for circulating and supplying the crude (meth)acrylic acid solution to the supply part from the storage part, and also includes a pressure meter in the circulate-supply tube. The device is used for carrying out dynamic crystallization in a batch manner by circulating the crude (meth)acrylic acid solution to flow the crude solution downward along the inner wall of the crystallization tube in a coating film-like state.

Device and process for crystallizing (meth)acrylic acid

PROBLEM An object of the present invention is to provide a crystallization unit capable of producing a purified acrylic acid having high purity efficiently. SOLUTION The present invention provides a crystallization unit to separate an acrylic acid-containing solution into a mother liquid and a purified acrylic acid, wherein the crystallization unit comprises a crystallizer having an exit to take out the mother liquid and the purified acrylic acid alternately; a supply line to supply the acrylic acid-containing solution to the crystallizer; and a recovery line to recover the mother liquid and the purified acrylic acid alternately from the crystallizer which is connected to the exit, and wherein the recovery line is equipped with an opening and closing unit consisting of a ball valve or a gate valve.

Crystallization unit for acrylic acid and method for crystallization of acrylic acid using the same

PROBLEM There is provided a melting method of (meth)acrylic acid crystal which is capable of providing a higher quality of (meth)acrylic acid without carrying out an additional purification treatment to (meth)acrylic acid obtained by a crystallization operation accompanied by melting of (meth)acrylic acid. In addition, there is provided a simple method for adjusting a content of polymerization inhibitor in a product (meth)acrylic acid. SOLUTION In the crystallization method melting (meth)acrylic acid crystal while wetting with the crystalline molten liquid, a polymerization inhibitor is added to a molten liquid melted after initiation of melting, and all of crystal is melted while circulating and feeding the molten liquid containing said polymerization inhibitor to the crystal. In addition, a content of polymerization inhibitor in product (meth)acrylic acid is adjusted by adding a predetermined amount of polymerization inhibitor corresponding to a product specification to the molten liquid melted after initiation of melting.

Method for crystallizing (meth)acrylic acid and method for regulating content of polymerization inhibitor in product (meth)acrylic acid

A process for producing (meth)acrylic acid of the present invention comprises the steps in the following order: a crystallization step of supplying a cooling medium cooled by a heat source device to a crystallizer to obtain a (meth)acrylic acid crystal from a crude (meth)acrylic acid solution; an adjustment step of returning the cooling medium discharged from the crystallizer to the crystallizer without cooling; a sweating step of supplying a heating medium to the crystallizer to partially melt the (meth)acrylic acid crystal, thereby obtaining a melted liquid, and discharging the melted liquid from the crystallizer; and a melting step of supplying the heating medium to the crystallizer to melt the (meth)acrylic acid crystal, thereby obtaining purified (meth)acrylic acid. According to the present invention, purified (meth)acrylic acid with high purity can be obtained.

Process for producing (meth) acrylic acid

The objective of the present invention is to provide a process for production of (meth)acrylic acid with improved production efficiency by efficiently shifting from heating procedure to cooling procedure for a crystallizer. A process for production of (meth)acrylic acid according to the present invention is characterized in comprising the steps of crystallizing (meth)acrylic acid from a crude (meth)acrylic acid solution by using a batch type crystallizer, and melting the obtained (meth)acrylic acid crystal to obtain a (meth)acrylic acid melted liquid; wherein preliminary cooling of the crystallizer for the next crystallization step is started during transferring the (meth)acrylic acid melted liquid from the crystallizer.

Process for production of (meth)acrylic acid

[Problem] There is provided, in a process for producing acrylic acid having a catalytic gas-phase oxidation reaction step, a condensation step, a collection step, a distillation step, a crystallization step, an acrylic acid recovering step or the like, a production method for acrylic acid, in which contamination of acrylic acid with protoanemonin without providing any additional purification treatment to the resultant purified acrylic acid can be reduced. [Solution] The problems described above can be solved by providing the production method for acrylic acid comprising A) a step obtaining an acrylic acid-containing gas by a catalytic gas-phase oxidation reaction of gas containing a acrylic acid raw material; B) a step of obtaining the acrylic acid-containing solution by introducing the acrylic acid-containing gas to the collection column or the condensation column and performing collection or condensation; C) a step of obtaining the crude acrylic acid by introducing the acrylic acid-containing solution to the distillation column or the crystallizer and performing distillation or crystallization, wherein a step of heat treating the acrylic acid-containing solution or the crude acrylic acid containing 100 ppm by mass or more of protoanemonin, under the condition of 100&#xb0; C. or more of temperature, 1 hour or more of time and a step of introducing the heat-treated acrylic acid-containing solution or the crude acrylic acid to the collection column, the condensation column, the distillation column or the crystallizer, are included.

Method for producing acrylic acid, and method for producing hydrophilic resin and method for producing water-absorbing resin using production method thereof

The present invention provides a method for effectively preventing the precipitation related to manganese acetate in the pipe for sending a polymerization inhibitor and the like, and the polymerization of (meth)acrylic acid. A first method of the present invention for producing (meth)acrylic acid, characterized in comprising steps of: producing a (meth)acrylic acid-containing gas by catalytic vapor phase oxidation reaction; and obtaining a (meth)acrylic acid-containing fluid by providing the (meth)acrylic acid-containing gas into a condensation column or an absorption column; wherein manganese acetate is used as a polymerization inhibitor; manganese acetate is dissolved into a (meth)acrylic acid aqueous solution containing not more than 10% by mass of (meth)acrylic acid, and the like, to obtain a manganese acetate aqueous solution; and the manganese acetate aqueous solution is provided into the condensation column or the absorption column.

Method for producing (meth)acrylic acid

The objective of the present invention is to provide a method for inhibiting polymerization of (meth)acrylic acid and the like. By the method, the generation of deposit in a pipe, which is exclusively used for providing a solution of a dialkyldithiocarbamic acid copper salt to a distillation column and the like, is prevented, and the problems such as the clogging of the pipe and polymerization in the distillation column are solved. The method according to the present invention for inhibiting polymerization of (meth)acrylic acid and/or an ester thereof is characterized in comprising a step of inhibiting polymerization of (meth)acrylic acid and/or the ester thereof by using a solution of a dialkyldithiocarbamic acid copper salt dissolved in an organic solvent, wherein a content amount of copper sulfate in the solution of the dialkyldithiocarbamic acid copper salt is 100 ppm or less by mass.

Polymerization inhibition method

Chilled coolant is prepared by liquid coolant utilizing the latent heat generated by a gasification of liquefied propylene, for example, and this chilled coolant is used in heat exchangers which are used in a process for production of acrylic acid or acrolein. This method allows effective utilization of the latent heat which used to be discarded and permits a reduction of energy consumption of cooling required separately in the step for production. By recovering the chilled coolant with the liquid coolant, it makes possible to stabilize the gasification of propylene, etc. and consequently stabilize the production of acrylic acid. This invention consists of providing the method for the production of acrylic acid, etc. and the apparatus which make effective use of the latent heat generated in the steps of production.

Method for production of acrylic acid and apparatus for production of acrylic acid

A method for quickly starting up a reactor and a reactor system therefor are provided. A shell-and-tube reactor in the system is adapted to circulate a heat medium having a solid point in the range of 50-250&#xb0; C. to the outside of the reaction tubes and characterized by initiating temperature elevation of the reactor by introducing a gas of a temperature in the range of 100-400&#xb0; C. to the reaction tubes' side and then circulating the heat medium in a heated state to the outside of the reaction tubes. By introducing a gas of an elevated temperature preparatorily to the reaction tubes, it is made possible to prevent the heat medium after circulation from being solidified again and enable the reactor to be quickly started up.

Method for starting up reactor and reactor system

A vertical heat exchanger is described, which allows efficient elimination of the gas generated therein and efficient removal of the sludge accumulated therein. The vertical heat exchanger has at least part of one end of a vent pipe formed of an upper tube sheet part (an upper cover part in the case of a spiral heat exchanger) and the other end thereof connected outside the heat exchanger to an immediately adjacent fluid passing port passing the same fluid as the vent and/or at least part of one end of a drain pipe formed of a lower tube sheet part (a lower cover part in the case of a spiral heat exchanger) and the other end thereof connected outside the heat exchanger to an immediately adjacent fluid passing port passing the same fluid as the drain.

Vertical heat exchanger

A method for distilling (meth)acrylic acid and/or the ester thereof by withdrawing vapor generated in a distillation column by distillation from the top of the column, condensing the vapor to give a condensate, and circulating part of the condensate as reflux liquid into the distillation column from the top thereof, comprising the step of adding a polymerization inhibitor to said condensate and said reflux liquid. This method enables maintaining the purity and quality of (meth)acrylic acid and/or the ester thereof at a certain level or higher, suppressing generation of polymers in the rectification column and suppressing polymerization of the condensate obtained by distillation in the incident facilities of the column such as condenser, condensate tank, and the like. In addition, the method enables reduction in the amount of polymerization inhibitor used while suppressing polymerization in the intermediate distillation columns (except the final rectification column).

Method for distilling (meth)acrylic acid and/or the ester thereof

A perforated tray without downcomer having only a small deviation between the opening ratio based on the diameter of a column and the actual opening ratio and a perforated tray column without downcomer formed by disposing such perforated trays without downcomer are provided. The perforated trays without downcomer are characterized by having a ratio of (A)/(B) in the range of 1.1-1.5, wherein A denotes the opening ratio found from the standard pitch between centers of holes and (B) denotes the opening ratio based on the diameter of a column.

Perforated tray column without downcomer

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Himeji, Japan

Kazuhiko Sakamoto